Effect of cyclophosphamide on the response of chickens to a virulent strain of Marek's disease virus

Inhibition of Marek's Disease Virus Replication and Spread by 25-hydroxycholesterol and 27-hydroxycholesterol In Vitro

Marek's disease virus (MDV) causes a deadly lymphoproliferative disease in chickens, resulting in huge economic losses in the poultry industry. It has been suggested that MDV suppresses the induction of type I interferons and thus escapes immune control. Cholesterol 25-hydroxylase (CH25H), a gene that encodes an enzyme that catalyses cholesterol to 25-hydroxycholesterol (25-HC), is an interferon-stimulating gene (ISG) known to exert antiviral activities. Other oxysterols, such as 27-hydroxycholesterols (27-HC), have also been shown to exert antiviral activities, and 27-HC is synthesised by the catalysis of cholesterol via the cytochrome P450 enzyme oxidase sterol 27-hydroxylase A1 (CYP27A1). At 24 h post infection (hpi), MDV stimulated a type I interferon (IFN-α) response, which was significantly reduced at 48 and 72 hpi, as detected using the luciferase assay for chicken type I IFNs. Then, using RT-PCR, we demonstrated that chicken type I IFN (IFN-α) upregulates chicken CH25H and CYP27A1 genes in chicken embryo fibroblast (CEF) cells. In parallel, our results demonstrate a moderate and transient upregulation of CH25H at 48 hpi and CYP27A1 at 72hpi in MDV-infected CEF cells. A significant reduction in MDV titer and plaque sizes was observed in CEFs treated with 25-HC or 27-HC in vitro, as demonstrated using a standard plaque assay for MDV. Taken together, our results suggest that 25-HC and 27-HC may be useful antiviral agents to control MDV replication and spread.

The Importance of the Bursa of Fabricius, B Cells and T Cells for the Pathogenesis of Marek’s Disease: A Review

The importance of the bursa of Fabricius (BF) for the pathogenesis of Marek’s disease (MD) has been studied since the late 1960’s. In this review, the results of these studies are analyzed in the context of the developing knowledge of the immune system of chickens and the pathogenesis of MD from 1968 to 2022. Based on the available techniques to interfere with the development of the BF, three distinct periods are identified and discussed. During the initial period between 1968 and 1977, the use of neonatal bursectomy, chemical methods and irradiation were the main tools to interfere with the B lymphocyte development. The application of these techniques resulted in contradictory results from no effects to an increase or decrease in MD incidence. Starting in the late 1970’s, the use of bursectomy in 18-day-old embryos led to the development of the “Cornell model” for the pathogenesis of MD, in which the infection of B lymphocytes is an important first step in MD virus (MDV) replication causing the activation of thymus-derived lymphocytes (T cells). Following this model, these activated T cells, but not resting T cells, are susceptible to MDV infection and subsequent transformation. Finally, B-cell knockout chickens lacking the J gene segment of the IgY heavy chain gene were used to further define the role of the BF in the pathogenesis of MD.

Protective effects of Zhuyeqing liquor on the immune function of normal and immunosuppressed mice in vivo

Background

Zhuyeqing Liquor (ZYQL), a well-known Chinese traditional health liquor, has various biological properties, including anti-oxidant, anti-inflammatory, immunoenhancement and cardiovascular protective effects.

Methods

The protective effects of Zhuyeqing Liquor (ZYQL) on the immune function was investigated in vivo in normal healthy mice and immunosuppressed mice treated with Cyclophosphamide (Cy, 100 mg/kg) by intraperitoneal injection on days 4, 8 and 12. ZYQL (100, 200 and 400 mg/kg) was administered via gavage daily for 14 days. The phagocytotic function of mononuclear phagocytic system was detected with carbon clearance methods, the levels of interleukin-6 (IL-6) and interferon-gamma (IFN-γ) in serum were detected with Enzyme linked immunosorbent assay (ELISA). Immune organs were weighed and organ indexes (organ weight/body weight) of thymus and spleen were calculated. Meanwhile, the activity of lysozyme (LSZ) in serum and the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) in spleen tissue were measured.

Results

ZYQL significantly upgrades the K value for clearance of carbon particles in normal mice treated with ZYQL (400 mg/kg) and immunosuppressed mice treated with ZYQL (100, 200 and 400 mg/kg) together with Cy (100 mg/kg) in vivo. The treatment of ZYQL (100, 200 and 400 mg/kg) effectively increased the activity of serum lysozyme as well as promoted the serum levels of IL-6 and IFN-γ in normal mice and immunosuppressed mice. Furthermore, ZYQL (100, 200 and 400 mg/kg) had an antioxidant effects in immune system by enhancing the antioxidant enzyme activity of SOD, CAT and GSH-Px in vivo. In addition, ZYQL (100, 200 and 400 mg/kg) effectively elevated the Cy-induced decreased organ index (thymus and spleen).

Conclusions

The present work shows that the dose-dependent administration of ZYQL is capable of influencing immune responses, which implying that its valuable functional health may be attributed partly to its protective effects for the immune function.

Marek's disease--a model for herpesvirus oncology

The article will review the salient features of pathogenesis of Marek's disease in terms of sequential events which occur from the time of virus entry to the development of frank lymphomas. A hypothesis will be presented which will offer a credible explanation for this specific sequence of changes. Then, various factors which influence the incidence of neoplasms will be identified and the possible mechanisms by which they are influential will be discussed. These include the variable oncogenic properties of different virus strains, the influence of host genotype, and immune responses.

Correlation between in vivo and in vitro studies of modulation of resistance to experimental Candida albicans infection by cyclophosphamide in mice

Mice receiving a single injection of cyclophosphamide (150 mg/kg) 1 to 6 days before inoculation with viable Candida albicans showed an increased susceptibility to the challenge accompanied by a reduction in peripheral blood polymorphonuclear leukocytes and lymphocytes as well as in spleen cellularity. Several immunological in vitro functions also appeared to be dramatically depressed. Most of these hematological and functional parameters returned to control values by day 9 after cyclophosphamide administration, at a time when resistance to C. albicans infection appeared to be unchanged. However, when exposure to cyclophosphamide occurred 12 to 21 days before inoculation with the live yeast, enhanced resistance was observed with the majority of the animals surviving challenge. To gain some insight into the mechanisms underlying this late increase in resistance to C. albicans infection after cyclophosphamide administration, we analyzed a series of immunological functions, including the in vitro candidacidal activity of polymorphonuclear neutrophils and plastic-adherent and nonadherent spleen cells as well as the activity of natural killer cells and alloreactive T lymphocytes. The results show that a numerical rebound of blood polymorphonuclear neutrophils and the appearance of a highly candidacidal cell population in the spleen may be among the factors underlying the late increase in resistance to C. albicans after administration of cyclophosphamide.

Influence of the bursa of Fabricius on the pathogenesis of Marek's disease

A series of experiments was conducted to study the influence of embryonal bursectomy (EBX) on the early and late pathogenesis of Marek's disease (MD). The early lytic infection in the lymphoid organs normally associated with oncogenic MD virus infection in intact chickens was not seen in EBX chickens. Therefore, the damage to the immune system was minimal. EBX chickens also had lower viremia levels, higher lymphocyte responses to mitogens, and a lower or delayed MD mortality when compared with intact chickens. Furthermore, it was shown that although vaccination with SB-1 by itself did not protect against a highly virulent MD transplantable tumor, the combination of EBX and vaccination gave significant protection. All these effects could be explained by an enhanced immune response in EBX birds. In contrast, the pathogenesis of nononcogenic MD virus was not influenced by EBX. The possible mechanism(s) involved in these observed effects of EBX on MD pathogenesis are discussed.